Grantee Research Project Results
Final Report: A Compact, Modular Wastewater Treatment System for Non-Potable Reuse of Household Greywater
EPA Contract Number: 68HERC22C0004Title: A Compact, Modular Wastewater Treatment System for Non-Potable Reuse of Household Greywater
Investigators: Rogers, Tate W
Small Business: Triangle Environmental Health Initiative
EPA Contact: Richards, April
Phase: I
Project Period: December 1, 2021 through May 31, 2022
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) Phase I (2022) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Water
Description:
Triangle Environmental (TE) has developed a compact, modular system for the rapid and fully automated treatment of domestic greywater for onsite non-potable reuse. Non-potable water resources can be utilized for a variety of applications within and outside of homes and commercial buildings. Simply replacing the demand for toilet flushing with non-potable water can offset approximately 25% of the total potable water use in a residential building, and up to 75% in a commercial building. Other potential non-potable uses include irrigation, cooling/heating applications, process water, and clothes washing.
The Phase I efforts for this project focused on modifying a technology already well-developed for onsite blackwater treatment towards greywater treatment and implementing it at household scale for applications with a high likelihood of rapid adoption (toilet flushing and laundry), thereby reducing household consumption of potable water by ~40% (73,000 L per year for a family of four). The system has a high potential for successful application in urban settings because it treats water rapidly and reliably in an appliance-like footprint amenable to limited indoor space and has a high level of readiness as it is based on a previously tested and verified process.
Summary/Accomplishments (Outputs/Outcomes):
The testing system utilized full (household) scale components. Greywater solutions used for testing were a combination actual greywater from homes (laundry and bath waters) and a synthetic mixture representative of total combined greywater sources following a recipe defined by a national standardization agency which uses this same mixture for testing greywater treatment systems (National Sanitation Foundation, Standard NSF 350-1). Each component in the system's three-stage process was tested individually which these greywater sources and optimized to meet final targets before the complete process was utilized to treat each greywater source. A summary of these results is shown in Table 1.
The fully integrated system was able to successfully treat the household and synthetic greywaters tested, demonstrating the expected performance consistent with team members' previous experience using the system for blackwater treatment. TSS was completely removed from each greywater solution (laundry effluent, bath/shower water, NSF "Challenge Recipe"). Similarly, COD was reduced by 91-100% for all three greywater sources, which ranged in initial concentrations from 45-2060 mg/L, and all demonstrated final values of < 50 mg/L. To test the robustness and disinfection capabilities of the total system, fully integrated testing of all subcomponents was performed with high-strength laundry greywater. These experiments demonstrated that bacteria MPN could be reduced from 1.5 x 107 to below detection level, suggesting that the latent chloride concentrations in solution were sufficient to provide full disinfection.
Table 1. Greywater system performance regarding TSS, COD, and Bacteria reduction for three different greywater sources: laundry effluent, bath/shower water, and NSF 350-1 "Challenge Recipe" greywater.
| TSS (mg/L) | COD (mg/L) | Bacteria (MPN) | |||
Test Water | Greywater | Effluent | Greywater | Effluent | Greywater | Effluent |
Laundry | 107 | 0 | 2060 | 29 | 1.5 x 10^7 | Non-Detect |
Bath/Shower | 1.7 | 0 | 45 | Non-Detect |
| |
NSF | 100 | 0 | 330 | 12 |
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Contaminant removal and operational data (i.e., flow rates, power, pressure) were used to determine final system sizing and input requirements These findings were then used to determine complete system materials, capital expenditures (CapEx), and operational expenditures (OpEx). Finally, system CapEx and OpEx was modeled in multiple use-case scenarios considering a range of utility rates in the United States to determine feasibility.
Conclusions:
Representative greywater was treated through the complete system process train which demonstrated that it was capable of achieving national and international standards for effluent reuse (NSF 350-1, ISO 30500). Based on the system achieving its targets with multiple input streams, it was proven to be technically viable in multiple use-case scenarios. Further, the projected system final design based on Phase I results is within an obtainable capital (CapEx) and operational expenditure (OpEx) range prior to manufacturing optimization, showing economic viability.
If awarded, Phase II will incorporate findings from Phase I research into the design, build, and testing of a pilot scale system(s) for treatment of household and commercial greywater streams. OpEx modeling identified energy consumption and consumables as the key sensitivities. Phase II technical development would focus on optimizing operational regimes to decrease pumping energy and prolonging life of consumables to further decrease system OpEx and increase the system’s ability to provide a quick return on investment in a wider range of market applications.
The primary market application for this technology is onsite non-potable reuse of greywater from residential or commercial sources which is currently an expanding market and is expected to continue to grow due to increasing water scarcity concerns throughout the United States and abroad. Global water recycling and reuse markets were projected to double from $12.2 billion in 2016 to $22.3 billion in 2021. Greywater reuse regulations in the United States are expanding to allow for more onsite non-potable reuse applications driven by the increasing pressure on water resources. The proposed greywater system provides an onsite, on-demand alternative to existing cost-prohibitive and high-maintenance greywater treatment systems. In addition, many of these existing decentralized greywater treatment systems are installed in rural or peri-urban areas where there is greater access to land for larger footprint systems. Therefore, there is a quickly emerging market opportunity for an appliance-like greywater treatment system that can be utilized by residences and businesses in dense, urban settings.
SBIR Phase II:
A compact, modular treatment system for non-potable re-use of residential and commercial greywaterThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.